Why did the US adopt a space policy to prevent Atlas/Delta from launching crew? Besides being a convenient way to maintain excess, expensive launch capacity, did anyone think that solids and crew would not be mixed in the future rockets? Since Earth departure is a very small part of LOC....perhaps yes.

I left the linked portion of that quote because it is relevant as seen below.

Why did the US adopt a space policy to prevent Atlas/Delta from launching crew? Besides being a convenient way to maintain excess, expensive launch capacity, did anyone think that solids and crew would not be mixed in the future rockets? Since Earth departure is a very small part of LOC....perhaps yes.

a) each LV would all have their "separate" task- e.g. keep everything separate to retain excess capacity Ares I for LEO crew, HLV for BEO, Atlas Delta for DOD, sats.....very very convenient indeed....

b) Separating human rated space exploration from unmanned payload launch will achieve reliable and affordable space access (e.g. no crew on Atlas/Delta in 2004...Falcon did not exist) - Falcon likely will show that common configurations without 3 engine product lines and no solids is one affordable and reliable way to fly Class A cargo and Crew... - 10 flights to reach $100M/flight with Vulcan...

c) Ares I could not loft crew safely, so much for Crew LV with shuttle solids.. so how about that 422/CST-100?

Yes less energy in the Atlas solids creates a smaller debris field volume but really the same physics (F=ma include drag, etc) ....at what time can they explode wrt chute deployment? Why even bother with all of this? Oops i forgot, the USG cannot tell the private sector what to do (too many regulations and all) with taxpayer funds.

Why is the addition of the skirt such a problem. Heck, it's not much and is short. I'd call it a mini-skirt myself. They're just making a safe, reliable launch system safer. Wouldn't you feel safer going up on an Atlas than any other rocket?

What I meant here was there's a big deal being made of this yet if I were an astronaut heading to space and the engineers said we need to add a skirt, I'd take it as a positive. They found something of concern and dealt with it, even though it adds cost, mass and maybe delay. Full credit to them pleaseAs for making the LV safer, the mini skirt reduces loads on the Centaur making the LV safer when this particular payload is launched. You must expect changed conditions if you do away with the fairing. What would you expect?The various kinds of Atlas vehicles haven't had an outright failure causing total loss of a payload since 93. That's got to count for something. Right now I myself wouldn't trust the F9 or Antares with the cheapest of payloads. With time, I expect I'll change my mind about that if they begin to show some reliability. I would have felt the same about Atlas back in 93. 23 years helps to allay my fearsI hope none of them suffer another launch failure

As for making the LV safer, the mini skirt reduces loads on the Centaur making the LV safer when this particular payload is launched. You must expect changed conditions if you do away with the fairing. What would you expect?

In my view, a better solution would have been to properly position the payload to begin with, allowing a longer tapered fairing (or whatever solution solved the problem) that would have prevented the aero-loading in the first place. This aeroskirt is a tacked-on fix to save schedule (re-positioning the payload would have meant rebuilding the service tower and redesigning umbilicals) for a problem that shouldn't even exist.

As for making the LV safer, the mini skirt reduces loads on the Centaur making the LV safer when this particular payload is launched. You must expect changed conditions if you do away with the fairing. What would you expect?

In my view, a better solution would have been to properly position the payload to begin with, allowing a longer tapered fairing (or whatever solution solved the problem) that would have prevented the aero-loading in the first place. This aeroskirt is a tacked-on fix to save schedule (re-positioning the payload would have meant rebuilding the service tower and redesigning umbilicals) for a problem that shouldn't even exist.

- Ed Kyle

Pardon me? Should not exist? This little problem with CST-100 is not the first time (and IMO it will not be the last either) that a given stack-design turns out to have aero-acoustic trouble identified late in the game.

In my view, a better solution would have been to properly position the payload to begin with, allowing a longer tapered fairing (or whatever solution solved the problem) that would have prevented the aero-loading in the first place. This aeroskirt is a tacked-on fix to save schedule (re-positioning the payload would have meant rebuilding the service tower and redesigning umbilicals) for a problem that shouldn't even exist.

- Ed Kyle

Pardon me? Should not exist? This little problem with CST-100 is not the first time (and IMO it will not be the last either) that a given stack-design turns out to have aero-acoustic trouble identified late in the game.

I can't think of an example from any past vehicle that required such a substantial, and atypical, add-on to the design.

Quote from Tory Bruno on reddit regarding skirt: "The capsule is optimized for its in space mission. The skirt is not really there to make a smooth aerodynamic profile. Its primary job is to move the reattachment of the shock further down the rocket so it will not overload Centaur's soda can thin skin"

Orion itself, with the SM fairings, changes in SM design, etc, but I don't think that SLS itself has seen substantial changes - at least not visible hardware changes.

- Ed Kyle

You're looking at the difference between designing a spacecraft to go on top of a pre-existing launch vehicle design that is outside of the original use concept vs contemporaneous spacecraft and launch vehicle design.

You're looking at the difference between designing a spacecraft to go on top of a pre-existing launch vehicle design that is outside of the original use concept vs contemporaneous spacecraft and launch vehicle design.

My question is, why did the original design of CST-100 with the stumpy adapter pass muster? They wind tunnel tested it some time back and it was made the baseline design. What changed, and why?

You're looking at the difference between designing a spacecraft to go on top of a pre-existing launch vehicle design that is outside of the original use concept vs contemporaneous spacecraft and launch vehicle design.

My question is, why did the original design of CST-100 with the stumpy adapter pass muster? They wind tunnel tested it some time back and it was made the baseline design. What changed, and why?

- Ed Kyle

We don't know if it passed muster. Nothing could have changed, just more testing was done

Jim, correct me if I'm wrong, but wasn't the CST-100 supposed to be designed as a sort of "Orion Lite"?

Primarily for "shuttle" use to and from the ISS or any other manned facilities or craft that was put in orbit. While it shared many of the basic lines of the Orion, but never really intended to be used beyond LEO

Also, my impression was that it was supposed to be a sort of proof of principle craft, mostly to confirm the Orion design and be upgraded as it went. Sort of a Block I, II, and then III evolution into an Orion-like craft.